Small hollow in cheek or chin (6)
I believe the answer is:
dimple
'small hollow in cheek or chin' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for dimple that I've seen before include "Facial depression" , "Limped (anag.)" , "Slight depression (in the skin)" , "Chin indentation" , "Small natural hollow in a cheek" .)